The present invention relates to a variable configuration membrane, for high capacity autoclaves, and to a method for making the membrane.
As is known, in the hydraulic system field providing for the use of one or more autoclaves there are at present used, mainly, either fixed or inter-exchangeable membrane autoclaves.
In fact, while the air-cushion autoclaves have a longer duration and easier maintenance characteristics, the membrane autoclaves allow very large water amounts to be used.
In this connection it should be moreover pointed out that this broadly diffused use of membrane autoclaves is also due to the fact that, by properly designing the membrane, the operations of the pumps and, accordingly, the closure and opening surge currents can be greatly reduced.
Actually, as an autoclave system is operated, the membrane operates in a continuous way, with alternate expansion and compression cycles.
Thus, the life or time duration of such an autoclave will strictly depend on that of the membrane, since the latter will be the first to fail.
By exploiting the properties of elastomeric materials prior membranes have been constructed with a size much smaller than that of the vessel containing them.
Another aspect to be pointed out is that the autoclave manufacturers tend to design the modern autoclaves vessels with increasing diameters so as to increase the operating capacity thereof.
At present these high capacity autoclave systems include simple cylindric configuration autoclave vessels and the autoclave membranes are provided, at their bottom end, with a flange therethrough water can pass and, at their top end, with a hole for engaging the membrane to the metal vessel of the autoclave.
Moreover, the above membranes usually work in a vertical attitude and as they are filled by liquid as the autoclave is operated, the will assume, because of the gravity effect, a configuration projecting at the bottom, like that of a pear.
Under these conditions, great stresses of dynamic nature are generated, since the bottom of the membrane is thinned so as to fit the autoclave bottom.
The thinned membrane portion, moreover, will rub against the raw metal material of the autoclave vessel, so that the membrane can be torn.
Another portion of the membrane, also subjected to a great stress, is the portion thereof which is provided for connection to the top of the autoclave vessel, which is greatly stretched, since it must support the overall weight of the loaded water in addition to that of the membrane.
Another aspect to be considered, finally, is that the molding of great size rubber or elastomeric material articles involves the use of large size making systems and apparatus, which are consequently very expensive and which usually exploit the pressure molding technique.
The operation and maintenance of these large size pressure molding systems involve correspondingly high capital costs, as well a very long time for designing and testing optimum operation cycles and efficiently operating maintenance devices.
Moreover, in a pressure molding system, the end result is always related to the manual and mental skillness of the operator, and moreover such a pressure molding system generates high amounts of waste.